Control file multiplexing
Control file is one of the most important files in oracle database. It records the name of the database and other key configurations, as well as the location and status of all the data files and log files in the current database. It is a key file that must be found and used in the process of database startup. By default, there are two control files in the database, and the contents and sizes of the two control files are the same. In a production environment, it is common to build multiple copies of control files on different disks. It should be noted that no matter how many control files the database has, when the database starts, it will check all the control files, and only if the contents of these control files are consistent and undamaged can the database start successfully.
Method 1:
View the current control file of the database
SQL > show parameter control_files
NAME TYPE VALUE
Control_files string / u01/app/oracle/oradata/orcl/control01.ctl
/ u01/app/oracle/oradata/orcl/control02.ctl
two。 Modify control file
SQL > alter system set control_files='/u01/app/oracle/oradata/orcl/control01.ctl','/u01/app/oracle/oradata/orcl/control02.ctl','/u01/app/oracle/control/control03.ctl' scope=spfile
System altered.
3. Consistency shuts down database
SQL > shutdown immediate
4. Copy the control file to the appropriate directory in the operating system
[oracle@ymm oracle] $cp / u01/app/oracle/oradata/orcl/control01.ctl / u01/app/oracle/control/control03.ctl
5. Start the database
SQL > startup
6. View the current control file of the database
SQL > show parameter control_files
NAME TYPE VALUE
-
Control_files string / u01/app/oracle/oradata/orcl/control01.ctl
/ u01/app/oracle/oradata/orcl/control02.ctl
/ u01/app/oracle/control/control03.ctl
Method 2: modify the parameter file pfile
Generate pfile parameter file
SQL > show parameter spfile
NAME TYPE VALUE
Spfile string / u01/app/oracle/product/11.2.0/dbhome_1/dbs/spfileorcl.ora
SQL > create pfile from spfile
File created.
By default, both pfile and spfile are stored in the $ORACLE_HOME/dbs directory. Pfile begins with init and spfile begins with spfile.
two。 Consistency shuts down database
SQL > shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
3. Modify control file parameters in pfile
[oracle@ymm dbs] $vi initorcl.ora
4. Copy control file copy
[oracle@ymm control] $cp control03.ctl control04.ctl-- I copy in a relative path without adding a path
[oracle@ymm control] $ls
Control03.ctl control04.ctl
5. Regenerate spfile and start the database
SQL > create spfile from pfile
File created.
SQL > startup
ORACLE instance started.
Total System Global Area 730714112 bytes
Fixed Size 2231952 bytes
Variable Size 239075696 bytes
Database Buffers 482344960 bytes
Redo Buffers 7061504 bytes
Database mounted.
Database opened.
6. Check the status of control files
SQL > show parameter control_files
NAME TYPE VALUE
Control_files string / u01/app/oracle/oradata/orcl/control01.ctl
/ u01/app/oracle/oradata/orcl/control02.ctl
/ u01/app/oracle/control/control03.ctl
/ u01/app/oracle/control/control04.ctl
